Well…..after the comments from my last post regarding NEMA selection I've had a busy couple of weeks fitting an electronic leadscrew conversion to my roundhead Student. It is now fully fitted and I'm glad to say so far it is behaving perfectly.

I'm certainly not re-inventing the wheel here and all of the credit for software development etc belongs to James Clough. The information available and Youtube videos from Clough42 are first class – it was more the selection, and placement of components that was the challenge for me and this is probably most likely to be of interest to others on the forum.

I chose a NEMA 24 4NM servo motor and driver kit from stepper online, Omron encoder and 3D printed all of the pulleys.

The pulleys took a bit of trial and error to get right but I think they'll be strong enough. I used a pulley generator on Thingiverse and inserted the Colchester spline centre using Tinkercad. All pulleys printed at 40% infill.

I chose to drive the encoder 1:1 with 60T GT2 10mm wide pulleys. I am driving the leadscrew with a 3:1 24T – 72T HTD 5mm pitch 15mm wide pulley.

Clough42 uses a die cast box from Bud industries for the control box. I couldn't find one in the UK (and didn't think to get one from from Mouser US when I placed the order for the LaunchXL) but found that a Hammond one available in the UK has exactly the same dimensions although the corner radiuses are slightly different. I can live with that. I 3D printed the lid and printed the control button information on a laser label.

After much deliberation I went with a 36v switching PSU for the servo motor and got a din mount 5v PSU for the LaunchXL and enclosure fan. Component layout below:

It took ages to decide on where to place the motor but in the end I placed it between the main drive belts. This meant there was absolutely no modification of the lathe needed. It fits nicely with loads of adjustment available.

The encoder was slightly easier but care had to be taken to keep it inside the cover

Finished power box below. I thought the box was going to be overkill size wise but I'm glad I left some breathing space!

Control box sits nicely next to the vid control

I really enjoyed the project and am pleased with the results and consider the outlay worthwhile. Although I have most change gears it was a pain swapping them over and it is now nice to be able to select surfacing and facing speeds at the press of a button.

I hope everyone here is able to stay safe and well during the COVID-19 lockdown and hopefully get to make the most of some workshop time.

Kevin